Radio controlled or switch controlled garage door opening and closing mechanisms are well known in the art. Such devices usually include an electric motor connected by a gear box and a chain, screw or wire drive mechanism to the garage door. When actuated, the motor opens and closes the garage door as is desired. Most modern garage door openers, typical of those for use in residential areas, rely on the inability of the drive mechanism to be back driven by force applied to the door to keep the garage door in a closed position. This is true even though locking devices such as shown in CURRY, U.S. Pat. No. 2,562,176 and HAYWARD, U.S. Pat. No. 3,996,591 are available. In CURRY, a solenoid actuated as part of the opening sequence for the drive motor is used to open a locked device on the garage door whereas a 90.degree. rotating motor is used to withdraw and position door locking pins in HAYWARD.
Such locking devices, even though effective, must be included in the original garage door opener design and cannot be retrofitted conveniently to existing door opener installations. They also cannot necessarily provide lock mechanisms at positions on the garage door which are best able to resist unauthorized opening forces. Therefore, there has been a need for an auxiliary locking device for powered garage door openers which is easy to install, can be installed in conjunction with most garage door openers, and which can be installed by a homeowner with little initial or installation cost.